#include #include #include #include #include #include #include using namespace atcoder; using namespace std; namespace adaptor = boost::adaptors; using ll = long long; using ull = unsigned long long; using ld = long double; using vi = vector; using vvi = vector; using vvvi = vector; using vl = vector; using vvl = vector; using pii = pair; using pll = pair; using vpii = vector; using vpll = vector; using vstr = vector; constexpr ll INF_LL=1LL<<60; constexpr int INF_I=1LL<<30; #define rep(i,n) for(int i=0; i<((int)(n)); i++) #define reps(i,n) for(int i=1; i<=((int)(n)); i++) #define rrep(i,n) for(int i=((int)(n)); i>0; i--) #define rreps(i,n) for(int i=((int)(n)-1); i>=0; i--) #define vector_cin(x) for(auto &n : (x)) cin >> n #define ALL(x) (x).begin(), (x).end() #define YesNo(x) ((x) ? "Yes" : "No") #define pb emplace_back template bool next_combination(BidirectionalIterator first, BidirectionalIterator last, Compare comp, size_t r) { BidirectionalIterator subset = first + r; if (first == last || first == subset || last == subset) { return false; } BidirectionalIterator src = subset; while (first != src) { src--; if (comp(*src, *(last - 1))) { BidirectionalIterator dst = subset; while (*src >= *dst) { dst++; } std::iter_swap(src, dst); std::rotate(src + 1, dst + 1, last); std::rotate(subset, subset + (last - dst) - 1, last); return true; } } rotate(first, subset, last); return false; } template bool next_combination(BidirectionalIterator first, BidirectionalIterator last, size_t r) { using value_type = typename std::iterator_traits::value_type; return next_combination(first, last, std::less(), r); } template bool chmax(T &a, const T& b) { if (a < b){ a = b; return true; } return false; } template bool chmin(T &a, const T& b) { if (a > b){ a = b; return true; } return false; } ll ceilint(ll x, ll y) { // x/y の 切り上げ return (x + y - 1) / y; } void Main(); int main() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << std::fixed << std::setprecision(15); Main(); return 0; } //-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- void Main() { int N, X, Y; cin >> N >> X >> Y; X--;Y--; if (X > Y) swap(X, Y); vector dp(N, 0); dp[X] = 1; for (int i = 1; i < N; i++) if (i < 3) dp[i] += dp[i - 1]; else dp[i] += dp[i - 1] + dp[i - 3]; cout << dp[Y].val() << endl; }